Regular Expressions in Emojicode

[joeskeen]

⭐️ Proposed change

Most languages have some kind of built-in support or library for using regular expressions. It would be great to see this feature in Emojicode.

🤔 Rationale

A lot of recreational coding I've tried to do in Emojicode have been programming puzzles, many of which are solved more easily using regular expressions than other methods.

🕺 Example

I'm not sure what it would look like, whether it would be string based or its own syntax like in JavaScript.

[joeskeen]

I've been thinking more about this lately, and wonder if we could implement a package for regular expressions, rather than having it built-in to the language.

There are a few guides out there for writing a RegEx engine

• https://kean.blog/post/lets-build-regex
• https://deniskyashif.com/2019/02/17/implementing-a-regular-expression-engine/

We could also port an existing RegEx engine from another language.

Another (perhaps simpler) option would be to make a package that wraps/links to a C++ implementation.

[thbwd]

Sure, regular expressions don't require language support. Although a literal syntax for regular expressions is nice, it isn't necessary. Since the C++ standard library has regular expression support, wrapping that should be a straightforward way to implement this.

[sodiboo]

emogex? https://gist.github.com/Terrain2/e0336c76e0a62b2ae537dfb6ffe12935

[joeskeen]

I'm currently playing around with implementing an EmojiCode-native regular expressions library. I'm following this guide: https://kean.blog/post/lets-build-regex and taking inspiration from emogex (from the comment above) and emojex, while trying to make it feel as EmojiCode-native and natural as possible. When I have more to share, I will (I'm in very early stages of writing the parser in EmojiCode). I'm currently stuck by #204.

[joeskeen]

I've taken another stab at it, and I'm happy to say I have a very early working alpha of regular expressions for EmojiCode. You can check it out here: https://gist.github.com/joeskeen/98c9f0e9d04cd6f32d27015e1b88b589. Please note that its feature set is not complete when compared to some other languages, but it does work with a lot of the standard regex use cases.

All special characters in this implementation of regex are emoji, and each emoji was chosen to align with similar concepts in EmojiCode (there's a table explaining the syntax at the bottom of the Gist). Here's my sample usage test file for anyone's edification if they would like to try it out:

📜 🔤regex.🍇🔤

🏁🍇
    🔤🍇he🤜❌❌🔡👐❌❌🔢👐❌❌🍇🤛🔘o a🤜cat👐dog🤛🍺❌❌⚫🍬b🍺R🔘❌❌🔡❌❌🔢🍺❌❌🍉🍿0123🍆⚪🔘AAA🍉🔤 ➡️ pattern
    🔤he🍇0eo adogcatdogdog bbbbbbbbbbbbj009🍉2~~AAA🔤 ➡️ string

    🆕🔭❗ ➡️ regex
    😀 🔤Searching...
    string   '🧲string🧲' 
    pattern  '🧲pattern🧲'🔤 ❗
    👀regex pattern string❗ ➡️ result
    ↪️ 👌result❓ 🍇
        😀 🔤Success at index 🧲🍺🐽result❓🧲🔤 ❗
    🍉 🙅 🍇
        😀 🔤No match found🔤 ❗
    🍉
🍉

For you RegEx buffs out there, the pattern I'm using is equivalent to

^he(\w|\d|\🍇)*o a(cat|dog)+\s?b+R*\w\d+\🍉[0123].*AAA$

This outputs:

Searching...
    string   'he🍇0eo adogcatdogdog bbbbbbbbbbbbj009🍉2~~AAA' 
    pattern  '🍇he🤜❌🔡👐❌🔢👐❌🍇🤛🔘o a🤜cat👐dog🤛🍺❌⚫🍬b🍺R🔘❌🔡❌🔢🍺❌🍉🍿0123🍆⚪🔘AAA🍉'
Success at index 0

I would like to write a ton of unit tests, then look at refactoring it a bit to allow features to be grouped together (rather than having one line in every method). Once I can get that working as intended, I'd like to add more features (like capturing groups) and propose it to be included in the package listing at https://www.emojicode.org/docs/packages/.

I would welcome any feedback anyone has!

A HUGE thanks to "clumsy computer" on YouTube for his live-stream implementation of a regex engine in Python. I gained the understanding, coded along with him in TypeScript, got it working the way I wanted to, then translated it into EmojiCode.

[joeskeen]

Wrote 271 unit tests, and fixed a handful of bugs! Feeling pretty good about the currently implemented functionality. (I updated the gist with the bug fixes, and the unit tests.)